Robert schorr



UNITED STATES PATENT OFFICE.

ROBERT SOHORR, OF URTEMBERG, GERMANY.

METHOD OF PRODUCING COLORED IMPRESSIONS.

SPECIFICATION forming part of Letters Patent No. 446,004, dated February10, 1891.

Application filed September 18,1889.

do away with'the inaccuracies which now occur in the lithographicprocess.

My method consists, briefly stated, of photographing the picture to beprinted and developing the negatives thereof to different intensities,according to the strength of the color to be employed in the printing,and transferring such colored impressions upon the stone or zinc plateby the usual method of points.

The method of multiplying pictures now in use for lithographic work isto employ a lithographer to make a water-color drawing of the picture tobe printed, and then to transfer the picture disintegrated into separatecolors upon lithographic stones for printing purposes. The disadvantageof this system is that there are often very gross mistakes in suchreproductions, owing to the inaccuracies .of execution of thelithographer.

By my method I take a number of photographs of the picture to beproduced and develop the negatives to diiferent intensities by length ofexposure to the light. These negatives of different intensities, whichare to form the basis for the color-plates, are so developed that theycan be adapted to a stronger or fainter color, as the case de mands.From the above described negatives as many photographs on glass aretaken as there are color-plates required for the picture. Thesephotographs are called dia positives, as they appear positive on the opposite side of the glass negative. These diaposit-ives are now retouchedby means of a brush or pencil corresponding to the single colorsemployed in the reproduction of the picture and corresponding to theplates made by hand by the lithographers. The next step is to transferthese plates to the stones or zinc plates; but as they are negativesthat is, what is white in the picture would appear black on the stones-adirect transfer cannot be performed, To avoid this dif- Serial No.324,345. (No specimens.)

upon the stone (photolithograph) or upon the zinc plate (autotype) andis ready to be etched. The etched stone or zinc plate is supplied withcolor by means of a roller, such color being rolled in, and is now readyfor printing. By printing the different colors upon each other thereproduction of the picture in its natural colors is produced.

The advantages of my method are to multiply the production of picturesby the process of lithography or book-printing without employing alithographer, thus eliminating any possible e ror and producing an exactrepresentation by photography. Further, my method can be employed eitherin lithography or by the aid of zinc plates.

Therefore, having described my invention, what I claim is Theherein-described method of producing a multiplication of pictures intheir original colors by lithographyor book-printing,which consists inphotographing the picture, producing therefrom a series of negatives ofvarying intensity, then producing from these negatives by photography aseries of dia-positives of varyingintensities, (upon glass,) thentouching up the said dia-positives with the color corresponding to theintensity of the plate, then reducingthe dia-positives to negatives byphotography, and finally transferring the same upon the lithographicstone or zinc plate and printing one color upon another until thepicture is produced in colors, substantially as and for the purposes setforth.

The foregoing specification ofmy invention signed by me this 2d day ofSeptember, 1889.

ROBERT SOHORR.

Witnesses:

THEODORE Annnnnnr, B. RUPMAN.

